This application claims priority from European Patent Application No. 04 012 165.9 filed May 22, 2004, hereby incorporated by reference in its entirety.
Coated substrates, for example coated architectural glasses or coated synthetic films, have altered optical properties after their coating. Whether or not these optical properties meet the desired properties can be determined by the corresponding measurements. Subsequent determination of the optical properties, i.e. after one or several layers have already been deposited on the substrate, at that point can only serve for the purpose of separating good coatings from the poor ones. The intent is therefore of acquiring, if possible, the optical properties already during the coating process in order to intervene in the coating process itself if necessary.
A spectrophotometer configuration is already known with which, while maintaining measuring accuracy with a single measuring and evaluating system, a relatively large number of measuring objects can be acquired within a closed chamber (DE 34 06 645 C2). Herein several measuring sites, which are disposed in a closed chamber, are connected through several fiber optic cables into a light resolving system. Through an associated movable diaphragm virtually any desired number of measuring sites or measuring objects can be acquired with this single light resolving system and the measuring results obtained here can be evaluated.
However, this photometer configuration is not suitable for the in-line measurement of substrates to be coated, which pass through several chambers.
A device is furthermore known for the production of coated transmission lines, in which a cable core is sequentially passed through four different types of chambers (DE 922 596). These are a metal vaporization chamber, metal layer thickness control chamber, insulation material vaporization chamber and insulation layer thickness control chamber. The control chambers serve for determining the thickness of a dielectric layer. Therein a control signal is generated through a directional light beam, which is emitted by a suitable light source and, via an optical system, is incident on the dielectric layer. The beam reflected from this layer is directed via a suitable optical system onto a photoelectric cell. The measuring device comprised of light source, optical system and photoelectric system is here distributed over an entire chamber.
In another known method for vacuum coating web-form transparent substrates, a substrate is coated at least once with a reflection layer and subsequently with at least one transparent layer (DE 100 19 258 C1). During or after the coating with the transparent layer, reflected light is measured in order to obtain information about the transparent layer, with the aid of which process parameters are adapted and/or layer parameters are controlled. The measuring device for the reflected light is located outside of a coating chamber and is disposed opposite the web-form substrate.
The invention, consequently, addresses the problem of measuring in coating installations comprised of several chambers the optical properties of coated substrates even during the coating process itself.
This problem is solved according to present invention.
The invention thus relates to a measuring device, which comprises several sequential coating chambers, for measuring optical properties of coated substrates. These coating chambers are separated from one another by partitioning walls, whose free end is disposed closely above the substrate. The substrate is preferably a continuous film. By measuring the reflection, the transmission, etc. of the substrate between the individual coating chambers, it is possible to carry out measurements within only partially completed layer systems. This yields advantages for the technical operation control of the coating process.
The advantage attained with the invention comprises in particular improving the process control. It is possible in complex optical layer systems to measure the reflection of a partial layer system after the first, second, third, etc. layer. This permits drawing direct conclusions regarding the quality of the layer thickness of the layer applied up to the time of measurement.
An embodiment example of the invention is depicted in the drawing and will be described in further detail in the following.